This invention relates to air blower assemblies for spa tubs and the like, and has particular reference to a safety control for preventing the overheating of the blower of such an assembly.
A popular feature of most spa tubs is the provision of an air blower assembly which delivers air to the tub through a pattern of small air holes that are formed in the underwater surfaces of the tub. The air issuing through these holes forms a pattern of bubbles, having an invigorating effect that enhances the user's enjoyment.
The air blower assembly typically has an electric motor that drives a blower at high speed, forcing air under pressure into the passages and forcing out the water that occupies the passages when the blower assembly is not in use. After an initial build-up of pressure sufficient to clear the water out of the air passages, the bubbling commences.
Such motors and blowers operate at high speed and generate a substantial amount of heat in normal operation. This heat normally is removed by the air flow through the blower assembly and past the motor, and does no harm. It sometimes happens, however, that a portion of the outlet passages becomes obstructed, for example, by people sitting in the spa, and this tends to reduce the cooling air flow past the motor. At the same time, the blockage produces an increase in the air pressure in the system, and the increased pressure also increases the temperature level in the system. As a result, there is a substantial danger of overheating in spa blower assemblies, with resultant danger of damage to the equipment, and in particular, of burning out of the motor.
The primary objective of the present invention is to protect the spa blower assembly from overheating while at the same time providing for a full flow of air to the spa.